Ultrafine-Grained Superconductors.
Abstract
Measurements of the effect of strain on the critical current of NbN show that almost no degradation occurs even at the highest strain levels, 0.5%, and the highest fields, 22T, that could be applied. Data at 4.2K in pulsed fields of over 30T suggest that the enhanced critical field measured in ultrafine-grained NbN films are due to a dimensional effect. Data on laser annealed Nb-Ge films further elucidated the role of second-phase pinning in enhancing the critical currents in these films. Electron beam annealing did not enhance significantly the critical current density. Pseudobinary V-Si-C alloys with critical temperatures of 17K were prepared by C-implantation of vanadium-rich V-Si films and subsequent annealing. A theory of current distribution near the end of a filamentary conductor and the effect on ac losses was developed. Some features of the anomalous SAW attenuation measured in NbN films were explained using the Kosterlitz-Thouless theory. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 04, 1982
- Accession Number
- ADA110979
Entities
People
- A. I. Braginski
- J. R. Gavaler
- M. Ashkin